JP-A-2011-253269 (PATENT LITERATURE 1) is a background art of the present invention, PATENT LITERATURE 1 discloses that “A three-dimensional model design assistance system includes a design rule storage unit for registering a design rule using an attaching direction of a three-dimensional model and a three-dimensional model storage unit for registering a name, a kind, a direction, an assembly order, adjacency information, and the like of a component output from the three-dimensional model of a product. The three-dimensional model design assistance system checks the design rule by using the attaching direction of the three-dimensional model and informs an operator of whether the three-dimensional model violates the design rule” (refer to ABSTRACT).